This invention generally relates to a compressor inlet valve, and more particularly, to an electronically controlled linear actuated inlet valve for an air compressor.
The application of air compressors for supplying compressed air to pneumatic construction equipment and to industrial plant compressed air networks usually requires that the compressor be equipped with some form of compressor throughput or capacity control. It is well known to employ a piston or poppet type inlet valve, i.e. those inlet valves having a piston engageable with a seat, in air compressor design to control the throughput or capacity of a respective compressor. An attendant benefit gained from using this type inlet valve in air compressor design is that the operational characteristics of this type inlet valve are generally more linear, as compared with, for example, a butterfly type inlet valve. However, during operation of an air compressor having such an inlet valve, there is a net load on the piston inlet valve which is caused by a pressure differential across the valve.
The pressure differential which exists across a conventional piston inlet valve is established by the existence of atmospheric pressure (P.sub.atm) on a first side of the piston and inlet pressure (P.sub.inlet) on a second side of the piston, where P.sub.inlet is less than P.sub.atm. Therefore, a net load force (F.sub.net load) is exerted on the piston inlet valve. A shortcoming of a net loaded inlet valve is that an inlet valve control system must continuously, throughout compressor operation, compensate for the net load, which is typically accomplished through use of a predetermined control force (F.sub.control), such that F.sub.control equals F.sub.net load.
To date, piston type inlet valves have been controlled by pneumatic or hydraulic control systems because these type control systems are able to effectively generate a continuous F.sub.control of sufficient magnitude to stabilize the inlet valve in a predetermined position. Although such pneumatic or hydraulic control systems have operated with varying degrees of success, it is desirable to control compressor inlet valves with sensitive electronic controllers to increase compressor efficiency. However, sensitive electronic inlet valve control systems do not function effectively in such instances when these electronic control systems must continuously overcome a net load force (F.sub.net load).
The foregoing illustrates limitations known to exist in present air compressor inlet valve designs. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.